CVE-2026-20301

Published Aug 5, 2026

Last updated 17 hours ago

Overview

Description
A vulnerability in the Extensible Messaging Client Protocol (XMCP), also referred to as the External Client protocol, of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of malformed XMCP packets. An attacker could exploit this vulnerability by sending a malformed XMCP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload unexpectedly, resulting in a DoS condition. The attacker does not need the XMCP client username to exploit this vulnerability.
Source
psirt@cisco.com
NVD status
Analyzed
Products
ios, ios_xe

Risk scores

CVSS 3.1

Type
Secondary
Base score
8.6
Impact score
4
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Severity
HIGH

Weaknesses

psirt@cisco.com
CWE-606

Social media

Hype score
Not currently trending

Configurations